Corrosion at low moisture content in both carbonated and chloride polluted concrete – Villa E-1027, a case study

Elisabeth Marie-Victoire,Myriam Bouichou,M.G Grantham,C Mircea

doi:10.1051/matecconf/201928910007

Abstract

Corrosion in reinforced concrete is generally attributed to either carbonation or chloride presence in the vicinity of the bars. But in the field of cultural heritage, especially for the most ancient monuments, it is not rare to encounter both carbonated and chloride polluted concrete, inducing heavy corrosion, as was the case in the Villa E-1027 in Roquebrune-Cap-Martin, on the French Mediterranean seashore. The villa was designed by Eileen Gray and Jean Badovici between 1926 and 1929. Due to aggressive environmental conditions and a period of dereliction, the concrete of the villa was quite heavily decayed and a deep restoration was led between 2000 and 2006. But after a little more than 10 years, and despite active maintenance, the villa is again facing corrosion induced decay. Prior to the definition of a new restoration protocol, to better evaluate the corrosion activity, in 2017 a permanent monitoring of moisture and temperature both in the air and in the concrete was installed. In the meantime, a series of instant electrochemical measurements was performed from 2017 to 2018. A first analysis of the results of the monitoring and the non-destructive tests clearly evidences that probably due to the conjunction of the carbonation of the concrete and external active chloride pollution, corrosion can happen at quite low moisture content.

Highlights

If carbonation induced corrosion and chloride induced corrosion were extensively studied as separate mechanisms [1] [2] [3] [4], research on their combined pollution, which is often encountered in the field of historic concrete, is rare [5]
In France, among the 850 historic monuments made of concrete, 27 % are concerned by chloride pollution and most of them are affected by carbonation [7]
The temperature and relative humidity monitoring evidenced a certain stability in the concrete on the two zones examined (Fig. 21) both on a daily and a yearly basis, so that the non-destructive instant electrochemical measurements could be extrapolated to the whole year, and were indicative of active corrosion in both the balcony and the beam examined

Summary

Introduction

If carbonation induced corrosion and chloride induced corrosion were extensively studied as separate mechanisms [1] [2] [3] [4], research on their combined pollution, which is often encountered in the field of historic concrete, is rare [5]. For the latter, carbonation is usual, and can affect the concrete cover up to several centimetres [6].When chlorides, either linked to sea proximity or to de-icing salts, reach the reinforcing bars, heavy corrosion can occur. Eleven years after this restoration and despite periodic maintenance, the concrete was again decaying due to rebar corrosion

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